[PATCH] MIPS: Go back with the default Linux # of registers to 90

["Maciej W. Rozycki" <macro@imgtec.com>]

Set the number of registers for non-XML-described Linux targets to 90, 
reverting a change made here with the addition of DSP register support:

commit 1faeff088bbbd037d7769d214378b4faf805fa2e
Author: Maciej W. Rozycki <macro@linux-mips.org>
Date:   Thu Mar 1 22:19:48 2012 +0000

and fixing a regression introduced for legacy `gdbserver' targets 
causing a "Remote 'g' packet reply is too long" error message where the 
amount of register data received with a `g' packet (90) exceeds the 
maximum number of registers expected (79).

Update the setting for XML-described targets, reflecting the actual 
number of registers which have been assigned numbers, matching the:

      gdb_assert (gdbarch_num_regs (gdbarch) <= MIPS_RESTART_REGNUM);

requirement in `mips_linux_init_abi'.

	gdb/
	* mips-tdep.c (mips_gdbarch_init): For GDB_OSABI_LINUX set 
	`num_regs' to 90 rather than 79.  Where a target description is 
	present adjust the setting appropriately.
---
Orgad,

 Can you please check if this change addresses your problem?

 I'm not currently set up to fully regression-test this change with 
`gdbserver', but I did some manual testing and things look right.  The 
change for `num_regs' in the XML-described case (which is now either 72 or 
79, for non-DSP and DSP targets respectively, rather than always 79) is in 
particular going to be always overridden in `mips_linux_init_abi' with 
`MIPS_RESTART_REGNUM + 1' (80) anyway -- we don't have proper support for 
XML-described bare-metal targets, so only the Linux target matters.  So I 
think this patch is safe and I'm going to install it once I've got a 
confirmation that the legacy case has been addressed.

  Maciej

gdb-mips-gdbarch-init-linux-num-regs.diff
Index: binutils/gdb/mips-tdep.c
===================================================================
--- binutils.orig/gdb/mips-tdep.c	2016-04-18 11:53:07.592133428 +0100
+++ binutils/gdb/mips-tdep.c	2016-04-18 12:30:58.698574753 +0100
@@ -8192,7 +8192,7 @@ mips_gdbarch_init (struct gdbarch_info i
       mips_regnum.dspctl = -1;
       dspacc = 72;
       dspctl = 78;
-      num_regs = 79;
+      num_regs = 90;
       reg_names = mips_linux_reg_names;
     }
   else
@@ -8311,6 +8311,8 @@ mips_gdbarch_init (struct gdbarch_info i
 	  return NULL;
 	}
 
+      num_regs = mips_regnum.fp_implementation_revision + 1;
+
       if (dspacc >= 0)
 	{
 	  feature = tdesc_find_feature (info.target_desc,
@@ -8344,6 +8346,8 @@ mips_gdbarch_init (struct gdbarch_info i
 
 	      mips_regnum.dspacc = dspacc;
 	      mips_regnum.dspctl = dspctl;
+
+	      num_regs = mips_regnum.dspctl + 1;
 	    }
 	}